Lens module

ABSTRACT

A lens module includes a first lens, a second lens, and a third lens comprising a convex object-side surface and a convex image-side surface. The lens module also includes a fourth lens including a concave object-side surface and a concave image-side surface, a fifth lens including a concave object-side surface, and a sixth lens including an inflection point formed on an image-side surface thereof. The first to sixth lenses are sequentially disposed from an object side to an image side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/974,997, filed on Dec. 18, 2015, which claims the benefit under 35USC § 119(a) of Korean Patent Application No. 10-2014-0184401 filed onDec. 19, 2014, with the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND 1. Field

The following description relates to a lens module having an opticalsystem including six lenses.

2. Description of Related Art

A lens module mounted in a camera of a mobile communications terminalincludes a plurality of lenses. For example, a lens module includes sixlenses in order to configure an optical system having high resolution.

However, when the optical system having high resolution is configured anincreased number of the plurality of lenses as described above, alength, which is a distance from an object-side surface of a first lensto an image plane of the optical system increases. In this case, itwould be difficult to mount the lens module in a slim mobilecommunications terminal. Therefore, the development of a lens modulehaving an optical system of decreased length is in demand.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In accordance with an embodiment, there is provided a lens module,including: a first lens; a second lens; a third lens including a convexobject-side surface and a convex image-side surface; a fourth lensincluding a concave object-side surface and a concave image-sidesurface; a fifth lens including a concave object-side surface; and asixth lens including an inflection point formed on an image-side surfacethereof, wherein the first to sixth lenses are sequentially disposedfrom an object side to an image side.

The first lens may include a meniscus shape with a convex object-sidesurface.

The second lens may include a meniscus shape with a convex object-sidesurface.

The fifth lens may include a convex image-side surface.

The sixth lens may include a convex object-side surface.

The sixth lens may include a concave image-side surface.

The lens module may also include a stop positioned between the secondand third lenses.

80<FOV≤120 may be satisfied, where FOV is a field of view of an opticalsystem including the first to sixth lenses.

15<V2 may be satisfied, where V2 is an Abbe number of the second lens.

The first lens may include a negative refractive power, the second lensmay include a positive refractive power or a negative refractive power,the third lens may include a positive refractive power, the fourth lensmay include a negative refractive power, the fifth lens may include apositive refractive power, and the sixth lens may include a negativerefractive power.

The third lens may have a refractive power stronger than a refractivepower of the fifth lens.

The third lens may have a refractive power stronger than a refractivepower of the second lens and fifth lens.

The image-side surface of the sixth lens may be concave in a paraxialregion and gradually curves to be convex at an edge portion thereof.

In accordance with an embodiment, there is provided a lens module,including: a first lens including a negative refractive power; a secondlens including a negative refractive power; a third lens including apositive refractive power; a fourth lens including a negative refractivepower; a fifth lens including a refractive power; and a sixth lensincluding a negative refractive power, wherein the first to sixth lensesare sequentially disposed from an object side to an image side.

The fifth lens may include a positive refractive power.

The fourth lens may include a concave object-side surface.

The third lens may be a convex object-side surface and a conveximage-side surface.

The fourth lens may include a concave image-side surface.

d4/d3<0.7 may be satisfied, where d3 is a thickness of the second lens,and d4 is a distance from an image-side surface of the second lens to anobject-side surface of the third lens.

1.0<(r3+r4)/(r3−r4) may be satisfied, where r3 is a radius of curvatureof an object-side surface of the second lens, and r4 is a radius ofcurvature of an image-side surface of the second lens.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a view of a lens module, according to a first embodiment;

FIG. 2 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 1;

FIG. 3 illustrates graphs having curves representing modulation transferfunction (MTF) characteristics of the lens module illustrated in FIG. 1;

FIG. 4 illustrates a table representing characteristics of lensesillustrated in FIG. 1;

FIG. 5 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 1;

FIG. 6 illustrates a view of a lens module, according to a secondembodiment;

FIG. 7 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 6;

FIG. 8 illustrates graphs having curves representing MTF characteristicsof the lens module illustrated in FIG. 6;

FIG. 9 illustrates a table representing characteristics of lensesillustrated in FIG. 6;

FIG. 10 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 6;

FIG. 11 illustrates a view of a lens module according to a thirdembodiment;

FIG. 12 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 11;

FIG. 13 illustrates graphs having curves representing MTFcharacteristics of the lens module illustrated in FIG. 11;

FIG. 14 illustrates a table representing characteristics of lensesillustrated in FIG. 11;

FIG. 15 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 11;

FIG. 16 illustrates a view of a lens module, according to a fourthembodiment;

FIG. 17 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 16;

FIG. 18 illustrates graphs having curves representing MTFcharacteristics of the lens module illustrated in FIG. 16;

FIG. 19 is a table representing characteristics of lenses illustrated inFIG. 16; and

FIG. 20 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 16.

FIG. 21 illustrates a view of a lens module, according to a fifthembodiment;

FIG. 22 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 21;

FIG. 23 illustrates graphs having curves representing MTFcharacteristics of the lens module illustrated in FIG. 21;

FIG. 24 is a table representing characteristics of lenses illustrated inFIG. 21; and

FIG. 25 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 21.

FIG. 26 illustrates a view of a lens module, according to a sixthembodiment;

FIG. 27 illustrates graphs having curves representing aberrationcharacteristics of the lens module illustrated in FIG. 26;

FIG. 28 illustrates graphs having curves representing MTFcharacteristics of the lens module illustrated in FIG. 26;

FIG. 29 is a table representing characteristics of lenses illustrated inFIG. 26; and

FIG. 30 illustrates a table representing conic constants and asphericcoefficients of the lens module illustrated in FIG. 26. Throughout thedrawings and the detailed description, unless otherwise described, thesame drawing reference numerals will be understood to refer to the sameelements, features, and structures. The relative size and depiction ofthese elements may be exaggerated for clarity, illustration, andconvenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/ormethods described herein will be apparent to one of ordinary skill inthe art. For example, the sequences of operations described herein aremerely examples, and are not limited to those set forth herein, but maybe changed as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various lenses, these lenses shouldnot be limited by these terms. These terms are only used to distinguishone lens from another lens. These terms do not necessarily imply aspecific order or arrangement of the lenses. Thus, a first lensdiscussed below could be termed a second lens without departing from theteachings description of the various embodiments.

In the following lens configuration diagrams, thicknesses, sizes, andshapes of lenses may be exaggerated for clarity. Particularly, theshapes of spherical surfaces and aspherical surfaces, as illustrated inthe lens configuration diagrams, are only illustrated by way of example,but are not limited to those illustrated in the drawings.

In some configurations, lenses included in lens modules are formed ofplastic or polycarbonate, a material lighter than glass. In otherconfigurations, some of the lenses included in the modules are formed ofplastic or polycarbonate, and other lenses may be formed of glass.According to some configurations, a lens module may include four or morelenses in order to achieve high levels of resolution in images beingcaptured.

In addition, in accordance with an embodiment, a first lens refers to alens closest to an object (or a subject), while a sixth lens refers to alens closest to an image plane (or an image sensor). Further, anobject-side surface of each lens refers to a surface thereof closest toan object (or a subject), and an image-side surface of each lens refersto a surface thereof closest to an image plane (or an image sensor).Further, in the present specification, all of radii of curvature,thicknesses, OALs (optical axis distances from an object-side surface ofthe first lens to the image plane), (a distance on the optical axisbetween a stop and an image sensor) SLs, IMGHs (image heights), and BFLs(back focus lengths) of the lenses, an overall focal length of anoptical system, and a focal length of each lens are indicated bymillimeters (mm).

Additionally, thicknesses of lenses, gaps between the lenses, OALs, andSLs are distances measured based on an optical axis of the lenses.Further, in a description for shapes of the lenses, a surface of a lensbeing convex is one in which an optical axis portion of a correspondingsurface is convex, and a surface of a lens being concave is one in whichan optical axis portion of a corresponding surface is concave.Therefore, although it is described that one surface of a lens isconvex, an edge portion of the lens may be concave. Likewise, althoughit is described that one surface of a lens is concave, an edge portionof the lens may be convex. In other words, a paraxial region of a lensmay be convex, while the remaining portion of the lens outside theparaxial region is either convex, concave, or flat. Further, a paraxialregion of a lens may be concave, while the remaining portion of the lensoutside the paraxial region is either convex, concave, or flat.

A lens module includes an optical system with a plurality of lenses. Forexample, the optical system of the lens module includes six lenseshaving refractive power. However, the lens module is not limited to onlyincluding the six lenses. For example, the lens module may include othercomponents that do not have refractive power, such as a stop controllingan amount of light. As another example, the lens module includes aninfrared cut-off filter filtering infrared light. As another example,the lens module may further include an image sensor, for example, animaging device, to convert an image of a subject incident thereonpassing through the optical system into electrical signals. As anotherexample, the lens module may further include a gap maintaining memberadjusting a gap between lenses. In one illustrative embodiment, the gapmaintaining member adjusts each lens to be at a distance from each otherand the filter. However, in an alternative embodiment, the gapmaintaining member may adjust each lens so that at least two of thelenses are in contact with each other, while the other lenses and thefilter have a predetermined gap there between. In a further embodiment,the gap maintaining member may adjust each lens so that at least two ofthe lenses are in contact with each other, while the other lenses have agap there between and at least one of the lenses is in contact with thefilter.

First to sixth lenses are formed of materials having a refractive indexdifferent from that of air. For example, the first to sixth lenses areformed of plastic or glass. At least one of the first to sixth lenseshas an aspherical surface shape. As an example, the sixth lens of thefirst to sixth lenses has the aspherical surface shape. As anotherexample, at least one surface of all of the first to sixth lenses isaspherical. In one example, the aspherical surface of each lens may berepresented by the following Equation 1:

$\begin{matrix}{Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {Fr}^{14} + {Gr}^{16} + {Hr}^{18} + {{Jr}^{20}.}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In an example, c is an inverse of a radius of curvature of acorresponding lens, K is a conic constant, and r is a distance from acertain point on an aspherical surface to an optical axis in a directionperpendicular to the optical axis. In addition, constants A to Jsequentially refer to 4th order to 20th order aspheric coefficients. Inaddition, Z is a distance between the certain point on the asphericalsurface at the distance r and a tangential plane meeting the apex of theaspherical surface of the lens.

The optical system configuring the lens module may have a wide field ofview (FOV) of 80 degrees or more. Therefore, the lens module, accordingto the embodiment, is configured to easily photograph a wide backgroundor object.

The lens module includes the first to sixth lenses. In addition, thelens module further includes a filter and an image sensor. Next, theabove-mentioned components will be described. In accordance with anillustrative example, the embodiments described of the optical systeminclude six lenses with a particular refractive power. However, a personof ordinary skill in the relevant art will appreciate that the number oflenses in the optical system may vary, for example, between two to sixlenses, while achieving the various results and benefits describedhereinbelow. Also, although each lens is described with a particularrefractive power, a different refractive power for at least one of thelenses may be used to achieve the intended result. Each of the firstthrough sixth lenses has a refractive power, either negative orpositive. For instance, in one configuration, the first lens has arefractive power. For example, the first lens has a negative refractivepower.

The first lens has a meniscus shape. For example, the first lens has ameniscus shape of which a first surface (object-side surface) is convexand a second surface (image-side surface) is concave.

The first lens may have an aspherical surface. For example, bothsurfaces of the first lens are aspherical. The first lens is formed of amaterial having high light transmissivity and excellent workability. Forexample, the first lens may be formed of plastic or an organic polymer.However, a material of the first lens is not limited to plastic. Forexample, the first lens may be formed of glass.

The second lens has a refractive power. For example, the second lens hasa positive refractive power. Alternatively, the second lens has anegative refractive power.

The second lens has a meniscus shape. For example, the second lens has ameniscus shape of which the object-side surface is convex and theimage-side surface is concave.

The second lens has an aspherical surface. For example, an image-sidesurface of the second lens is aspherical. The second lens is formed of amaterial having high light transmissivity and excellent workability. Forexample, the second lens is formed of plastic or other organic polymer.However, a material of the second lens is not limited to plastic. Forexample, the second lens is formed of glass.

The second lens is formed of a material having a low refractive index.For example, the second lens is formed of a material having an Abbenumber of 20 or more. The second lens formed of this materialeffectively corrects chromatic aberration caused by the first lens.

The third lens has a refractive power. For example, the third lens has apositive refractive power.

One surface of the third lens is convex. As an example, the object-sidesurface of the third lens is convex. As another example, the image-sidesurface of the third lens is convex. As another example, both surfacesof the third lens are convex.

The third lens has an aspherical surface. For example, both surfaces ofthe third lens are aspherical. The third lens is formed of a materialhaving high light transmissivity and excellent workability. For example,the third lens is formed of plastic or glass.

The fourth lens has a refractive power. For example, the fourth lens mayhave negative refractive power.

One surface of the fourth lens is concave. For example, the object-sidesurface of the fourth lens is concave. As another example, theimage-side surface of the fourth lens is concave. As another example,both surfaces of the fourth lens may be concave.

The fourth lens has an aspherical surface. For example, both surfaces ofthe fourth lens are aspherical. The fourth lens is formed of a materialhaving high light transmissivity and excellent workability. For example,the fourth lens is formed of plastic or glass.

The fifth lens has a refractive power. For example, the fifth lens mayhave positive refractive power.

The fifth lens has a meniscus shape. For example, the fifth lens has ameniscus shape of which the object-side surface is concave and theimage-side surface is convex.

The fifth lens has an aspherical surface. For example, both surfaces ofthe fifth lens are aspherical. The fifth lens is formed of a materialhaving high light transmissivity and excellent workability. For example,the fifth lens may be formed of plastic or glass.

The sixth lens has a refractive power. For example, the sixth lens has anegative refractive power.

One or more inflection points are formed on at least one of anobject-side surface and an image-side surface of the sixth lens. As anexample, the object-side surface of the sixth lens is convex at thecenter of an optical axis, but may be concave in the vicinity of theoptical axis. As another example, the image-side surface of the sixthlens is concave at the center of the optical axis, but may be convex inthe vicinity of the optical axis. For instance, the image-side surfaceof the sixth lens is concave in a paraxial region and gradually curvesto be convex at an edge portion thereof.

The sixth lens has an aspherical surface. For example, both surfaces ofthe sixth lens are aspherical. The sixth lens is formed of a materialhaving high light transmissivity and high workability. For example, thesixth lens may be formed of plastic or glass.

A person of ordinary skill in the relevant art will appreciate that eachof the first through sixth lenses may be configured in an oppositerefractive power from the configuration described above. For example, inan alternative configuration, the first lens has a positive refractivepower, the second lens has a negative refractive power, the third lenshas a negative refractive power, the fourth lens has a positiverefractive power, the fifth lens has a negative refractive power, andthe sixth lens has a positive refractive power.

The filter filters a partial wavelength from incident light incidentthrough the first to sixth lenses. For example, the filter is aninfrared cut-off filter filtering an infrared wavelength of the incidentlight. The filter is formed of plastic or glass and has an Abbe numberof 60 or more.

The image sensor realizes a high resolution of 1300 megapixels. Forexample, a unit size of the pixels configuring the image sensor may be1.12 μm or less.

The lens module configured as described above has a wide field of view.For example, the lens module has a field of view of 80 degrees or more.In addition, the lens module has a relatively short length. For example,an overall length TTL, which is a distance from the object-side surfaceof the first lens to the image plane of the lens module is 4.60 mm orless. Therefore, the lens module, according to an embodiment, isadvantageously miniaturized.

The lens module satisfies the following Conditional Expression 1:

80<FOV≤120.  [Conditional Expression 1]

In one example, FOV is a field of view of the optical system includingthe first to sixth lenses.

The lens module satisfies at least one of the following ConditionalExpressions 2 and 3:

15<V2  [Conditional Expression 2]

V2<50.  [Conditional Expression 3]

In one example, V2 is an Abbe number of the second lens.

The lens module satisfies at least one of the following ConditionalExpressions 4 and 5:

d4/d3<0.7  [Conditional Expression 4]

d4/d3<0.4.  [Conditional Expression 5]

In one example, d3 is a thickness of the second lens, and d4 is adistance from the image-side surface of the second lens to anobject-side surface of the third lens.

The lens module satisfies at least one of the following ConditionalExpressions 6 and 7:

1.0<(r3+r4)/(r3−r4)  [Conditional Expression 6]

1.0<(r3+r4)/(r3−r4)<2.5.  [Conditional Expression 7]

In an example, r3 is a radius of curvature of an object-side surface ofthe second lens, and r4 is a radius of curvature of the image-sidesurface of the second lens.

The above Conditional Expressions 1 through 7 are conditions to optimizemanufacturing of the second lens. For example, in a case in which anumerical range depending on the above Conditional Expressions 1 through7 are satisfied, the second lens is easily manufactured.

A lens module, according to a first embodiment, will be described withreference to FIG. 1.

A lens module 100 includes an optical system including a first lens 110,a second lens 120, a third lens 130, a fourth lens 140, a fifth lens150, and a sixth lens 160. In addition, the lens module 100 alsoincludes an infrared cut-off filter 70 and an image sensor 80. Further,the lens module 100 further includes a stop (ST). For example, the stopis disposed between the second and third lenses.

In an embodiment, the first lens 110 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 120 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 130 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 140 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 150 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 160 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 160 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the third and fifth lenses 130 and 150 have positiverefractive power. In one example, a focal length (f3) of the third lens130 and a focal length (f5) of the fifth lens 150 have the followingrelationship therebetween. For example, the third lens 130 has arefractive power stronger than a refractive power of the fifth lens 150.

f3<f5  [Relational Expression 1]

In an embodiment, the first lens 110, the second lens 120, the fourthlens 140, and the sixth lens 160 have negative refractive power. In anexample, a focal length (f1) of the first lens 110, a focal length (f2)of the second lens 120, a focal length (f4) of the fourth lens 140, anda focal length (f6) of the sixth lens 160 have the followingrelationship thereamong:

f2<f1<f4<f6.  [Relational Expression 2]

FIGS. 2 and 3 are graphs having curves representing aberrationcharacteristics and modulation transfer function (MTF) characteristicsof the lens module, in accordance with an embodiment.

FIG. 4 is a table representing characteristics of the lenses configuringthe lens module. In FIG. 4, Surface Nos. S1 and S2 represent the firstsurface (object-side surface) and the second surface (image-sidesurface) of the first lens, and Surface Nos. S3 and S4 represent thefirst and second surfaces of the second lens. Similarly, Surface Nos. S5to S12 represent first and second surfaces of the third to sixth lenses,respectively. In addition, Surface Nos. S13 and S14 represent first andsecond surfaces of the infrared cut-off filter.

FIG. 5 is a table representing conic constants and aspheric coefficientsof the lenses configuring the lens module, in accordance with anembodiment. In FIG. 5, S1 to S12 are Surface Nos. of correspondingsurfaces of the first through sixth lenses, and K and A to G are conicconstants (K) and aspheric coefficients (A to G) of correspondingsurfaces of the first through sixth lenses.

A lens module, according to a second embodiment, will be described withreference to FIG. 6.

A lens module 200 includes an optical system including a first lens 210,a second lens 220, a third lens 230, a fourth lens 240, a fifth lens250, and a sixth lens 260. In addition, the lens module 200 furtherincludes an infrared cut-off filter 70 and an image sensor 80. Further,the lens module 200 further includes a stop (ST). For example, the stopis disposed between the second and third lenses.

In an embodiment, the first lens 210 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 220 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 230 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 240 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 250 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 260 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 260 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the third and fifth lenses 230 and 250 may havepositive refractive power. In one example, a focal length (f3) of thethird lens 230 and a focal length (f5) of the fifth lens 250 have thefollowing relationship therebetween. For example, the third lens 230 hasa refractive power stronger than a refractive power of the fifth lens250.

f3<f5  [Relational Expression 3]

In an embodiment, the first lens 210, the second lens 220, the fourthlens 240, and the sixth lens 260 have negative refractive power. In anexample, a focal length (f1) of the first lens 210, a focal length (f2)of the second lens 220, a focal length (f4) of the fourth lens 240, anda focal length (f6) of the sixth lens 260 have the followingrelationship thereamong:

f2<f1<f4<f6  [Relational Expression 4]

FIGS. 7 and 8 are graphs having curves representing aberrationcharacteristics and MTF characteristics of the lens module, inaccordance with an embodiment.

FIG. 9 is a table representing characteristics of the lenses configuringthe lens module. In FIG. 9, Surface Nos. S1 and S2 represent the firstsurface (object-side surface) and the second surface (image-sidesurface) of the first lens, and Surface Nos. S3 and S4 represent thefirst and second surfaces of the second lens. Similarly, Surface Nos. S5through S12 represent first and second surfaces of the third to sixthlenses, respectively. In addition, Surface Nos. S13 and S14 representfirst and second surfaces of the infrared cut-off filter.

FIG. 10 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module, in accordancewith an embodiment. In FIG. 10, S1 to S12 represent Surface Nos. ofcorresponding surfaces of the first through sixth lenses, and K and A toG represent conic constants (K) and aspheric coefficients (A to G) ofcorresponding surfaces of the first through sixth lenses.

A lens module, according to a third embodiment, will be described withreference to FIG. 11.

A lens module 300 includes an optical system including a first lens 310,a second lens 320, a third lens 330, a fourth lens 340, a fifth lens350, and a sixth lens 360. In addition, the lens module 300 furtherincludes an infrared cut-off filter 70 and an image sensor 80. Further,the lens module 300 includes a stop (ST). For example, the stop isdisposed between the second and third lenses.

In an embodiment, the first lens 310 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 320 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 330 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 340 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 350 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 360 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 360 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the second lens 320, the third lens 330, and the fifthlens 350 have positive refractive power. In an example, a focal length(f2) of the second lens 320, a focal length (f3) of the third lens 330,and a focal length (f5) of the fifth lens 350 have the followingrelationship thereamong. For example, the third lens 330 has arefractive power stronger than the refractive power of the second andfifth lenses 320 and 350.

f3<f5<f2  [Relational Expression 5]

In the present exemplary embodiment, the first lens 310, the fourth lens340, and the sixth lens 360 may have negative refractive power. Here, afocal length (f1) of the first lens 310, a focal length (f4) of thefourth lens 340, and a focal length (f6) of the sixth lens 360 may havethe following relationship thereamong:

f1<f4<f6  [Relational Expression 6]

FIGS. 12 and 13 are graphs having curves representing aberrationcharacteristics and MTF characteristics of the lens module, inaccordance with an embodiment.

FIG. 14 is a table representing characteristics of the lensesconfiguring the lens module. In FIG. 14, Surface Nos. S1 and S2represent the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4represent the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S12 represent first and second surfaces of the thirdto sixth lenses, respectively. In addition, Surface Nos. S13 and S14represent first and second surfaces of the infrared cut-off filter.

FIG. 15 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module, in accordancewith an embodiment. In FIG. 15, S1 to S12 represent Surface Nos. ofcorresponding surfaces of the first through sixth lenses, and K and A toG represent conic constants (K) and aspheric coefficients (A to G) ofcorresponding surfaces of the first through sixth lenses.

A lens module, according to a fourth embodiment, will be described withreference to FIG. 16.

A lens module 400 includes an optical system including a first lens 410,a second lens 420, a third lens 430, a fourth lens 440, a fifth lens450, and a sixth lens 460. In addition, the lens module 400 furtherincludes an infrared cut-off filter 70 and an image sensor 80. Further,the lens module 400 includes a stop (ST). For example, the stop isdisposed between the second and third lenses.

In an embodiment, the first lens 410 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 420 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 430 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 440 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 450 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 460 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 460 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the third and fifth lenses 430 and 450 have positive arefractive power. In an example, a focal length (f3) of the third lens430 and a focal length (f5) of the fifth lens 450 have the followingrelationship therebetween. For example, the third lens 430 has arefractive power stronger than that of the fifth lens 450.

f3<f5  [Relational Expression 7]

In an embodiment, the first lens 410, the second lens 420, the fourthlens 440, and the sixth lens 460 have negative refractive power. Here, afocal length (f1) of the first lens 410, a focal length (f2) of thesecond lens 420, a focal length (f4) of the fourth lens 440, and a focallength (f6) of the sixth lens 460 may have the following relationshipthereamong:

f2<f1<f4<f6  [Relational Expression 8]

FIGS. 17 and 18 are graphs having curves representing aberrationcharacteristics and MTF characteristics of the lens module, inaccordance with an embodiment.

FIG. 19 is a table representing characteristics of the lensesconfiguring the lens module, in accordance with an embodiment. In FIG.19, Surface Nos. S1 and S2 represent the first surface (object-sidesurface) and the second surface (image-side surface) of the first lens,and Surface Nos. S3 and S4 represent the first and second surfaces ofthe second lens. Similarly, Surface Nos. S5 to S12 represent first andsecond surfaces of the third through sixth lenses, respectively. Inaddition, Surface Nos. S13 and S14 represent first and second surfacesof the infrared cut-off filter.

FIG. 20 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module, in accordancewith an embodiment. In FIG. 20, S1 to S12 indicate Surface Nos. ofcorresponding surfaces of the first through sixth lenses, and K and A toG indicate conic constants (K) and aspheric coefficients (A to G) ofcorresponding surfaces of the first through sixth lenses.

A lens module, according to a fifth embodiment, will be described withreference to FIG. 21.

A lens module 500 includes an optical system including a first lens 510,a second lens 520, a third lens 530, a fourth lens 540, a fifth lens550, and a sixth lens 560. In addition, the lens module 300 furtherincludes an infrared cut-off filter 570 and an image sensor 580.Further, the lens module 300 includes a stop (ST). For example, the stopis disposed between the second and third lenses.

In an embodiment, the first lens 510 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 520 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 530 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 540 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 550 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 560 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 560 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the second lens 520, the third lens 530, and the fifthlens 550 have positive refractive power. In an example, a focal length(f2) of the second lens 520, a focal length (f3) of the third lens 530,and a focal length (f5) of the fifth lens 550 have the followingrelationship thereamong. For example, the third lens 530 has arefractive power stronger than the refractive power of the second andfifth lenses 520 and 550.

f2<f5<f3  [Relational Expression 5]

In the present exemplary embodiment, the first lens 510, the fourth lens540, and the sixth lens 560 may have negative refractive power. Here, afocal length (f1) of the first lens 510, a focal length (f4) of thefourth lens 540, and a focal length (f6) of the sixth lens 560 may havethe following relationship thereamong:

f4<f1<f6  [Relational Expression 6]

FIGS. 22 and 23 are graphs having curves representing aberrationcharacteristics and MTF characteristics of the lens module, inaccordance with an embodiment.

FIG. 24 is a table representing characteristics of the lensesconfiguring the lens module. In FIG. 24, Surface Nos. S1 and S2represent the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4represent the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S12 represent first and second surfaces of the thirdto sixth lenses, respectively. In addition, Surface Nos. S13 and S14represent first and second surfaces of the infrared cut-off filter.

FIG. 25 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module, in accordancewith an embodiment. In FIG. 25, S1 to S12 represent Surface Nos. ofcorresponding surfaces of the first through sixth lenses, and K and A toG represent conic constants (K) and aspheric coefficients (A to G) ofcorresponding surfaces of the first through sixth lenses.

A lens module, according to a sixth embodiment, will be described withreference to FIG. 26.

A lens module 600 includes an optical system including a first lens 610,a second lens 620, a third lens 630, a fourth lens 640, a fifth lens650, and a sixth lens 660. In addition, the lens module 300 furtherincludes an infrared cut-off filter 670 and an image sensor 680.Further, the lens module 300 includes a stop (ST). For example, the stopis disposed between the second and third lenses.

In an embodiment, the first lens 610 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 620 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 630 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 640 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is concave. The fifth lens 650 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 660 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the sixth lens 660 has an asphericalsurface shape in which inflection points are formed on an object-sidesurface and an image-side surface thereof, respectively.

In an embodiment, the second lens 620, the third lens 630, and the fifthlens 650 have positive refractive power. In an example, a focal length(f2) of the second lens 620, a focal length (f3) of the third lens 630,and a focal length (f5) of the fifth lens 650 have the followingrelationship thereamong. For example, the fifth lens 650 has arefractive power stronger than the refractive power of the second andthird lenses 620 and 630.

f2<f3<f5  [Relational Expression 5]

In the present exemplary embodiment, the first lens 610, the fourth lens640, and the sixth lens 660 may have negative refractive power. Here, afocal length (f1) of the first lens 610, a focal length (f4) of thefourth lens 640, and a focal length (f6) of the sixth lens 660 may havethe following relationship thereamong:

f4<f1<f6  [Relational Expression 6]

FIGS. 27 and 28 are graphs having curves representing aberrationcharacteristics and MTF characteristics of the lens module, inaccordance with an embodiment.

FIG. 29 is a table representing characteristics of the lensesconfiguring the lens module. In FIG. 29, Surface Nos. S1 and S2represent the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4represent the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S12 represent first and second surfaces of the thirdto sixth lenses, respectively. In addition, Surface Nos. S13 and S14represent first and second surfaces of the infrared cut-off filter.

FIG. 30 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module, in accordancewith an embodiment. In FIG. 30, S1 to S12 represent Surface Nos. ofcorresponding surfaces of the first through sixth lenses, and K and A toG represent conic constants (K) and aspheric coefficients (A to G) ofcorresponding surfaces of the first through sixth lenses.

Table 1 represents optical characteristics of the lens modules,according to the first to sixth embodiments. The lens module has anoverall focal length (f) of 1.8 to 2.4. A focal length (f1) of the firstlens is determined to be in a range of −7.0 to −2.0. A focal length (f2)of the second lens is determined to be in a range of −48 or more. Afocal length (f3) of the third lens is determined to be in a range of1.3 to 1.6. A focal length (f4) of the fourth lens is determined to bein a range of −5.0 to −2.0. A focal length (f5) of the fifth lens isdetermined to be in a range of 1.3 to 2.6. A focal length (f6) of thesixth lens is determined to be in a range of −3.0 to −1.0.

An overall length (TTL) of the optical system is determined to be in arange of 4.4 to 5.1. A field of view (FOV) of the lens module isdetermined to be in a range of 90 to 120.

TABLE 1 First Second Third Fourth Fifth Sixth Remarks EmbodimentEmbodiment Embodiment Embodiment Embodiment Embodiment f  2.326 2.2981.852 2.208 1.856 2.083 f1 −5.895 −5.573 −4.020 −6.339 −2.203 −3.279 f2−41.16 −37.38 11.11 −46.54 4.76 10.91 f3 1.419 1.414 1.469 1.435 1.4311.560 f4 −3.893 −4.005 −3.686 −3.831 −2.993 −3.520 f5 2.441 2.413 2.0712.446 1.700 1.423 f6 −2.468 −2.515 −2.634 −2.548 −1.826 −1.397 TTL 4.5024.500 4.500 4.500 4.800 5.000 FOV 91.79 92.48 104.68 94.76 120.00 120.00ImgH 2.400 2.400 2.400 2.400 2.390 2.390

Tables 1 and 2 represent numerical ranges of Conditional Expressions andvalues of Conditional Expressions 1 through 7 of the lens modulesaccording to the first through sixth embodiments.

TABLE 2 Conditional First Second Third Fourth Fifth Sixth ExpressionsEmbodiment Embodiment Embodiment Embodiment Embodiment Embodiment d4/d30.132 0.137 0.570 0.201 0.706 1.271 (r3 + r4)/(r3 − r4) 1.304 1.3173.650 1.503 5.795 −8.383

As seen in Tables 1 and 2, the lens modules, according to the first tosixth embodiments, satisfy all of the Conditional Expressions 1 through7.

As set forth above, according to embodiments, the optical system has ahigh resolution.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A lens module, comprising: a first lens; a secondlens; a third lens comprising a convex object-side surface and a conveximage-side surface; a fourth lens comprising a concave object-sidesurface and a concave image-side surface; a fifth lens comprising aconcave object-side surface; and a sixth lens comprising an inflectionpoint formed on an image-side surface thereof, wherein the first tosixth lenses are sequentially disposed from an object side to an imageside.
 2. The lens module of claim 1, wherein the first lens comprises ameniscus shape with a convex object-side surface.
 3. The lens module ofclaim 1, wherein the second lens comprises a meniscus shape with aconvex object-side surface.
 4. The lens module of claim 1, wherein thefifth lens comprises a convex image-side surface.
 5. The lens module ofclaim 1, wherein the sixth lens comprises a convex object-side surface.6. The lens module of claim 1, wherein the sixth lens comprises aconcave image-side surface.
 7. The lens module of claim 1, furthercomprising: a stop positioned between the second and third lenses. 8.The lens module of claim 1, wherein 80<FOV≤20 is satisfied, where FOV isa field of view of an optical system comprising the first to sixthlenses.
 9. The lens module of claim 1, wherein 15<V2 is satisfied, whereV2 is an Abbe number of the second lens.
 10. The lens module of claim 1,wherein the first lens comprises a negative refractive power, the secondlens comprises a positive refractive power or a negative refractivepower, the third lens comprises a positive refractive power, the fourthlens comprises a negative refractive power, the fifth lens comprises apositive refractive power, and the sixth lens comprises a negativerefractive power.
 11. The lens module of claim 1, wherein the third lenshas a refractive power stronger than a refractive power of the fifthlens.
 12. The lens module of claim 1, wherein the third lens has arefractive power stronger than a refractive power of the second lens andfifth lens.
 13. The lens module of claim 1, wherein the image-sidesurface of the sixth lens is concave in a paraxial region and graduallycurves to be convex at an edge portion thereof.
 14. A lens module,comprising: a first lens comprising a negative refractive power; asecond lens comprising a negative refractive power; a third lenscomprising a positive refractive power; a fourth lens comprising anegative refractive power; a fifth lens comprising a refractive power;and a sixth lens comprising a negative refractive power, wherein thefirst to sixth lenses are sequentially disposed from an object side toan image side.
 15. The lens module of claim 14, wherein the fifth lenscomprises a positive refractive power.
 16. The lens module of claim 14,wherein the fourth lens comprises a concave object-side surface.
 17. Thelens module of claim 14, wherein the third lens is a convex object-sidesurface and a convex image-side surface.
 18. The lens module of claim14, wherein the fourth lens comprises a concave image-side surface. 19.The lens module of claim 14, wherein d4/d3<0.7 is satisfied, where d3 isa thickness of the second lens, and d4 is a distance from an image-sidesurface of the second lens to an object-side surface of the third lens.20. The lens module of claim 13, wherein 1.0<(r3+r4)/(r3−r4) issatisfied, where r3 is a radius of curvature of an object-side surfaceof the second lens, and r4 is a radius of curvature of an image-sidesurface of the second lens.